Clip retainer

ABSTRACT

A clip retainer held by a resilient tab in a groove of a hub for limiting the movement of a control valve in the hub and for holding a diaphragm against the hub. Upon actuation of the control valve, fluid under pressure is permitted to flow to one side of the diaphragm. A pressure differential is created across the diaphragm causing the hub to move and transmit a force to an output member.

United States Patent Kytta [54] CLIP RETAINER [72] Inventor: Oswald 0.Kytta, South Bend, lnd.

Attorney-William N. Antoms and Plante, Hartz, [73] Assignee: The BendixCorporation. smith and Thompson [22] Filed: Dec. 21, 1970 ABSTRACT [211App]. No.: 99,795

- r A clip retainer held by a resilient tab in a groove of a hub forlimiting the movement of a control valve in Rial. 91/369 the hub and fordi a diaphragm g i the hub. Up ac uat o e control al' under p [58] newof Search "91/369 369 369 376 sure is permitted to flow to one side ofthe diaphragm. A pressure differential is created across the diaphragm[56] References (med causing the hub to move and transmita force to anUNITED STATES PATENTS output member- 2 3,385,167 5/1968 Wilson eta].;...9l/376 6Claims, 3 Drawing Figures /2 i I I F i 1' III,

1a., k f$g- -h a? I E, (4% 68 v a s v 84 2 3 76 78 1 Sept. 5, 1972Primary Examiner-Paul E. Maslousky PATENIEDSEP i n 1 3,688,647.

F i I INVENTOR. OSWALD 0- KYTTA A TTORNE Y5 CLIP RETAINER BACKGROUND OFTHE INVENTION Servomotors have been used to supply the driving force tomove a piston for pressurizing fluid to operate a power braking systemfor a number of years. To reduce the number of component parts that areneeded to produce a servomotor molded parts were developed. As disclosedin U. S. Pat. No. 3,125,003 the movable wall and hub member are moldedinto a single unit. The control valve carried in the hub is held inplace by a stop pin retained in the hub by the diaphragm. Later, asshown in copending U. S. Application Ser. No. 841,628 filed July 14,1969, now abandoned, the stop pin was replaced by a horseshoe shapedretainer which formed part of the passageway between the variablechamber, but still the position of this stop pin'depended upon thetolerance of a groove molded in the hub.

SUMMARY INVENTION DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Theservomotor shown in the FIG. 1 has a housing 5 formed by a front shell12 and a rear shell 14. The

In subsequent developments it was observed that the snap fitting of thediaphragm against the hub was not necessary since differential pressureacross the wall alone would force the diaphragm against the reinforcingplate to prevent communication of fluid pressure between the chambers.Thus, the diaphragm need only be held against the plate by a retainer. Ihave invented a means of securing the diaphragm to the hub. In myinvention a diaphragm retainer is positioned against the reinforcingplate by clip means which partially surrounds the hub. The clip meanshas an inner projection which fits in a slot in the hub to provide astop for limiting the extent of movement of the control valve uponrelease. A tab on the projection will bias the projection against onewall of the slot to prevent any play from developing between the controlvalve and the projection which would cause noise and unwanted wearbetween the parts.

It is therefore the object of this invention to provide a servomotorwith a single means for retaining the diaphragm against a plate heldagainst the hub and for providing a stop for limiting the movement ofthe control valve upon release of an actuating member.

It is still a further object of this invention to provide clip meanshaving a resilient member for biasing a projection against a wall of aslot to provide substantially a uniform engagement with a control valveupon release.

It is another object of this invention to provide the means forretaining a wall member against a hub to provide a differential pressureseal between a first and second chamber.

These and other objects will become apparent to those who read thespecification and view the drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a sectional view of aservomotor constructed in accordance with the principles of myinvention;

FIG. 2 is a sectional view taken along line 2-2 of FIG. 1 showing theclip retaining means for holding the diaphragm retainer and plateagainst the hub; and

FIG. 3 is a perspective view of the clip retaining means of the typeshown in FIG. 2.

housing 10 is divided by wall means 16 which separates the interiorthereof into a power chamber 18 and a control chamber 20. Hub means 22,which is slidably retained in the rear shell 14, is secured to wallmeans 16. Control valve means 24 upon actuation by push rod 26 by anoperator will interrupt communication between the front chamber 18 andthe rear chamber 20 by closing passageway 28 and permitting fluid underpressure to flow through internal bore 30 to passageway 32 into rearchamber 20. With fluid in the rear chamber 20 at a different pressurethan the fluid in front chamber 18, a differential pressure force willbe created across wall means 16. This differential pressure force willbe transmitted to the hub means 22 to cause it to move. Whenthe hubmeans 22 moves, an output force for pressurizing a master cylinder in abraking system (not shown) will be produced.

In more particular detail the hub means 22 includes, a cylindrical boss34 with a 1and 37 adjacent a shoulder 36 located in the internal steppedbore 30. A slot 38 adjacent the land 37 adjacent a shoulder 36 extendsto the periphery of the cylindrical boss 34. A radially extending flange40 having a first groove 42 concentric to the flange 40 and a secondgroove 44 of an inverted keyhole shape, shown in FIG. 2, surrounds thecylindrical boss 22.

The wall means 16 has a flexible diaphragm 46 which has a first bead 48sealingly retained between the front shell 12 and the rear shell 14 byperiodically having wing 50 crimped down against edge 52 of the frontshell 12. A second bead 54 of the diaphragm mates with concentric rib 56of the reinforcing plate 57. The reinforcing plate 57 has a smooth outerrim 59 which substantially conforms to the cylindrical shape of thehousing 10 and an inner edge 65 which conforms with the invertedkey-hole shaped groove 44. A cylindrical retainer member 64 having asimilar inverted key-hole shape holds the second head 54 of thediaphragm in the arcuate rib 56 of the plate.

The control valve means 24 located in the internal stepped bore 30 has aplunger member 61 which includes a keeper member 58 on the front faceand a rearwardly facing annular atmospheric valve seat 60 thereon on therear face for sealing abutment with a flexible annular rubber poppetmember 62. The annular rubber poppet member 62 surrounds a matching tube63 which transmits an actuation force to seat the poppet member 62. Thepoppet member 62 has an integral flexible diaphragm portion 66 with aradial outer periphery 68 which is enlarged for sealing engagement withthe sidewalls of the internal stepped bore 30. The rubber poppet member62 is biased against the atmospheric valve seat 60 by a coil spring 70that surrounds the push rod 26 and is interposed between flange 72 andshoulder 74. The control valve means 24 is retained in the deactivatedposition, as shown in FIG.

l, by a return spring 76 positioned between a retainer 78 held on pushrod 26 by shoulder 74 and a sealing annular washer 80 which biases theouter thickened portion 68 into sealing engagement with the sidewalls.

Upon actuation of the value means 24 by push rod 26 the keeper member 58slides along the land 37 with the flexible rubber poppet 62 firstseating on shoulder 82 which closes communication between the frontchamber 18 and the rearchamber 20 and then the valve seat 60 moves awayfrom .the poppet 62 to permit atmospheric pressure access to chamber 30from whence it flows through passageway 32 into the rear chamber 20 tocreate the pressure differential for operating the servomotor.

When the push rod 26 is released, the force of the return spring 76 willmove the valve means 24 to the right as viewed in FIG. 1. To maintainthe valve means 24 in the proper operating position in the bore 30, aclip retaining means 84 is positioned in slot 38. The clip retainingmeans 84 has a pair of prongs 86, and 87, as shown in FIGS. 2 and 3,which surround the stem section 88 of the keeper member 58 to provide asubstantial uniform support around the endkeeper member 58 for stoppingrearward movement when the valve means 24 is released. Tab 98 secured tothe center of clip retaining means will resiliently bias prongs 86 and87 against one side of the slot 38 to assure the keeper member isstopped in the same location after each application. By maintaining theprongs 86 and 87 snug against the slot 38, the possibility of a rattlebetween the parts and uneven wear on the parts is reduced after repeateduse. The clip retaining means 84 has a central said fluid under pressureflows, said hub means having a radially extending external flangeextending along the inner diameter of said flexible diaphragm, saidoutput rod being retained against a reaction member which abuts ashoulder of a land in said internal bore, said hub means having a slotadjacent said land extending to the periphery of said huh; I

keeper means attached to the control valve, said keeper means beinglocated to slide in an axial direction through the width of said land toposition said valve meanswithin said internal bore; and

clip means located in said slot having a central portion which extendsinto said internal bore to surround said control valve for limiting theextent of axial movement of said keeper means to substantially the widthof the land within said internal bore, said central portion having anarcuate projection extending past the periphery of said hub means atsaid slot, said clip means having a pair of arms secured to said arcuateprojection, each of said arms having a portion which snaps into a groovein said hub means to lock said clip means in a fixed position to retainsaid flexible diaphragm against said external flange, said externalflange transferring the force created by said pressure differentialthrough the hub means to said output rod.

2. In the servomotor, as recited in claim 1, wherein arcuate portion 90which extends past the periphery of the central portion of said clipmember includes:

the cylindrical boss 34 to hold plate retaining means 64 tight againstthe reinforcing plate 57. A pair of arms 94 and 96 attached to thecentral arcuate portion 90 of the clip retaining means 84 has a shape tosubstantially conform to the arcuate portion of the inverted key-holeshaped section of the boss 34 and end section 65 of the diaphragm plate57. Each of the arms 94 and 96 has a pro jection 97 which snaps into anindentation 100 on the cylindrical boss 34 to fix the position of theclip retaining means 84 in the inserted position. Each of the arms 94and 96 in conjinction with the central arcuate portion 90 help to holdretainer member 64 tight against the reinforcing plate 57 and seal 92 inthefirst groove 42 to assure a seal between the front and rear chambers18 and 20, respectively. Each of the arms 94 and 96 are identical toassure a tight fit even though in the process of assembly the locationof the tab 98 may in slot 38 be reversed. Thus, the clip retaining means84 will perform the dual duty of limiting the movement of the controlvalve and holding the diaphragm against the reinforcing plate to providea way of easily constructing a useable servomotor.

I claim:

1. In a servomotor having a housing divided by wall means into a controlchamber and a power chamber and operated by a control valve which allowsfluid pressure into the control chamber to create a pressuredifferential between the control chamber and the power chamber causingthe wall means to move and transmit a force to an output rod, the wallmeans including a flexible diaphragm, means for connecting the wallmeans to the output rod and for holding the control valve in anoperative position, said means comprising:

hub means having a stepped internal bore, said internal bore beingconnected to said control chamber and power chamber by passages throughwhich a resilient tab member for biasing said central portion in saidslot to inhibit axial movement of said central portion corresponding tomovement of said keeper means.

3. In the servomotor, as recited in claim 2, further including:

plate means having a central opening which surrounds said hub adjacentsaid external flange with a radially extending surface, said radiallyextend- .ing surface terminating in a peripheral rim substantiallyconcentric to said housing of the servomotor; and

a seal located between plate means and said external flange forpreventing fluid pressure from passing from the control chamber to thepower chamber,

. said plate means having a concentric rib which urges said seal againstsaid flange.

4. In the servomotor, as recited in claim 3, wherein said flexiblediaphragm includes:

a first bead secured to the housing of said servomotor with a centralportion overlying said plate means and a second head which mates withsaid concentric rib; and

a retainer member located between the arcuate pro- .jection on said clipmeans and said plate means for holding said second bead against said ribto maintain a seal between said control and said power chambers;

5. In the servomotor, as recited in claim 4, wherein said pair of armsact on said retainer member to hold said bead in said rib.

6. In the servomotor, as recited in claim 5, wherein said centralportion of said clip member extending into.

said bore includes:

a pair of prongs having a curved section for abutting the interior ofsaid bore when said arms are snapped in a locked position;

said pair of prongs providing a uniform support for stopping said keepermeans with the control valve in a released position.

l l l

1. In a servomotor having a housing divided by wall means into a controlchamber and a power chamber and operated by a control valve which allowsfluid pressure into the control chamber to create a pressuredifferential between the control chamber and the power chamber causingthe wall means to move and transmit a force to an output rod, the wallmeans including a flexible diaphragm, means for connecting the wallmeans to the output rod and for holding the control valve in anoperative position, said means comprising: hub means having a steppedinternal bore, said internal bore being connected to said controlchamber and power chamber by passages through which said fluid underpressure flows, said hub means having a radially extending externalflange extending along the inner diameter of said flexible diaphragm,said output rod being retained against a reaction member which abuts ashoulder of a land in said internal bore, said hub means having a slotadjacent said land extending to the periphery of said hub; keeper meansattached to the control valve, said keeper means being located to slidein an axial direction through the width of said land to position saidvalve means within said internal bore; and clip means located in saidslot having a central portion which extends into said internal bore tosurround said control valve for limiting the extent of axial movement ofsaid keeper means to substantially the width of the land within saidinternal bore, said central portion having an arcuate projectionextending past the periphery of said hub means at said slot, said clipmeans having a pair of arms secured to said arcuate projection, each ofsaid arms having a portion which snaps into a groove in said hub meansto lock said clip means in a fixed position to retain said flexiblediaphragm against said external flange, said external flangetransferring the force created by said pressure differential through thehub means to said output rod.
 2. In the servomotor, as recited in claim1, wherein the central portion of said clip member includes: a resilienttab member for biasing said central portion in said slot to inhibitaxial movement of said central portion corresponding to movemEnt of saidkeeper means.
 3. In the servomotor, as recited in claim 2, furtherincluding: plate means having a central opening which surrounds said hubadjacent said external flange with a radially extending surface, saidradially extending surface terminating in a peripheral rim substantiallyconcentric to said housing of the servomotor; and a seal located betweenplate means and said external flange for preventing fluid pressure frompassing from the control chamber to the power chamber, said plate meanshaving a concentric rib which urges said seal against said flange.
 4. Inthe servomotor, as recited in claim 3, wherein said flexible diaphragmincludes: a first bead secured to the housing of said servomotor with acentral portion overlying said plate means and a second bead which mateswith said concentric rib; and a retainer member located between thearcuate projection on said clip means and said plate means for holdingsaid second bead against said rib to maintain a seal between saidcontrol and said power chambers.
 5. In the servomotor, as recited inclaim 4, wherein said pair of arms act on said retainer member to holdsaid bead in said rib.
 6. In the servomotor, as recited in claim 5,wherein said central portion of said clip member extending into saidbore includes: a pair of prongs having a curved section for abutting theinterior of said bore when said arms are snapped in a locked position;said pair of prongs providing a uniform support for stopping said keepermeans with the control valve in a released position.